A pepper plant that produces no flowers, but has lush foliar growth may be receiving too much nitrogen. Nitrogen lends itself to growing dark leaves and stems, but does not aid, and may even hinder, fruit production. Peppers are known to thrive with over-fertilization, but not all plants respond the same to environmental conditions.
When the jalapeno plant flowers and drops the flowers without setting fruit, it is due to a condition called blossom drop. Blossom drop is caused by high temperatures, low temperatures and discrepancies in water availability. Jalapeno plants are tropical perennials that grow as annuals in the United States. Temperatures above 90 degrees Fahrenheit and nighttime temperatures lower than 60 degrees Fahrenheit may result in blossom drop. Jalapenos prefer moist soil, and allowing them to dry out while blooming may also cause blossom drop.
Jalapenos are small, conical peppers with thick walls and deep green color that ripens to red. They are usually picked and used before they ripen. Peppers that do not reflect the smooth, regular shape of most jalapenos may have suffered stress during bloom. Sometimes blossom drop does not happen, but flowers exposed to extreme heat during bloom produce deformed, irregularly shaped peppers.
Due to their native tropical habitat, peppers prefer hot temperatures, moisture and 12 to 16 hours of sunlight every day. For this reason they do best when grown in the United States when started indoors or in a greenhouse early in the spring, and later transplanted outdoors when the weather is warm and all danger of frost has passed. Pepper seedlings should be fertilized with a commercial or organic fertilizer when transplanted, and again after the first fruit set.